Given names from birth search of son on New Zealand BDM website in April 2022:
1922/14744. Rundell, Leslie Ian. Mother: Ivy May. Father: Maurice John

Cannot determine maiden name - no record of marriage could be found on the New Zealand BDM website as at April 2022.

Date and place of cremation from Bay of Plenty Tauranga records found in April 2022:
Rundell, Ivy May, Cremation 5 January 1979
Rundell, Maurice John, Cremation 12 January 1976 [Husband]
Rundell, Leslie Ian, Age 58, Cremation 28 April 1981 [Son]

Maiden name, date and place of marriage from Church of England marriage records found in April 2022:
Name: Ivy May Hutchings
Gender: Female
Marital Status: Spinster
Marriage Age: 25
Event Type: Marriage
Birth Date: 1893
Marriage Date: 25 Feb 1918
Marriage Place: West Chickerell, Dorset, England
Father: George Hutchings
Spouse: Maurice John Rundell

Birth record found in the England & Wales, Civil Registration Birth Index in April 2022:
Name: Ivy May Hutchings
Registration Date: 1893
Quarter of the Year: Jan-Feb-Mar
Registration Place: Newport, Monmouthshire, Wales

Place of birth from 1911 England Census found in April 2022:
Name: Ivy May Hutchings
Age in 1911: 18
Estimated Birth Year: abt 1893
Relation to Head: Niece
Gender: Female
Birth Place: Cwmbran, Wales
Civil Parish: Chickerell
Country: England
Street Address: Spring Cottage, East Street, Chickerell
Marital status: Single
Occupation: Assist Household Duties
Sub-registration District: Upway
Household Members:
William Trent Chaffer, Head, age 69, Police pensioner
Susan Chaffer, Wife, age 64
Ivy May Hutchings, Niece, age, assist household duties
William Charles Parry, Boarder, age 36
[NOTE: Birth place of “Cwmbran” was a town in South Wales lying within the boundaries of Monmouthshire, Wales].

Year and country of death, date of birth, from death search on New Zealand BDM website in April 2022:
1979/30091. Rundell, Ivy May. Date of birth: 20 February 1893

Full date of death of 3 January 1979 from further searching in April 2022 on BDM Search by incrementally changing the date range for the death.